Device for the reproduction of sound



Dec. 17,1929. c. H. DUFFY DsvcuFcR THE REPRODUCTION or SOUND Filed-Feb.` 28, 1929 DCC@ 17* 1929I ,c. HfDUFFY A DEVICE vFfm THE EFRODILCHON' 0F vs'oum:

--- -.-il -il /N vf/v ro@ CHAR-L55 HUGH OUA-,CV

w Y 477-0 ver PatemeafDec. 17, 1929 UNITED s'ra'rlazs CHARLES HUGH DU'EEY, 0E MIAML'ELQRIDA DEVICE Eon THE REPRODUCTION or SOUND Application led February 28., 1929. .Serial No. 343,424. 4

(GRANTED UNDER THE Aer or MARCH 3, 1883, As AMENJ'JED APRIL 3o, 192s; 37o o.'G. 757) The invention described herein may be. manufactured and used by or for the Government for governmental purposes, Without the payment to me of any royalty thereon.

5 reproduction of sound, but more particularly to radio loud speakers and the like, and

A`*has for its object to provide certain improvements in this class of devices. s In speakers having the type of diaphragm 1 to Which this invention is particularly, though not necessarily directed, I have found that the same'are Well suited for the application of a plurality of diaphragm driving or o actuating units, and this type of diaphragm Will therefore be employed asv illustrating the invention, though it is tovbe understood -that f the system'may be applied to or used in conl nection'vvith any suitable diaphragm forms or constructions.

A speaker diaphragm properly designed proportioned and constructed when cpnnected to an'eihcient actuating unit Will faithfully reproduce both high andloW frequenf cies Without'favoringleitheig that is f to say o Without accentuating either the highs or the lows, nor slighting either the highs or the lows.

Speakers, therefore as usually constructed D have their own peculiar characteristics and are capable, of course, of accommodating themselves to a considerable range in volumeY under the influence of the volume control with which all modern receiving sets are" equipped. This flexibility in volume, however, is simply a product of the amplitude of the impulses imparted to the diaphragm; the greater the amplitude thegreater the volume. The quality or the characteristics of the 40 sound reproduced is not thereby influenced,

or lto be more correct, is not intended to be changed or influenced by variations in the amplitude of the impulses imparted to the diaphragm`under the influence ofthe volume control of the receiving set. As a matter of fact rattling and distortion may be the result of too great volume and thus the quality and' characteristics of the sound maybe effected by amplitude or volumes But such change in quality andcharacteristics of the sound resharpen thedefinition, eliminate overtones .tion delivered at ,the different but adjacent 4produced is of no concern here, and the term quality and characteristic? of sound Whenever appearing in the specification and l -the claims will have no reference to such im- This invent-ion relates to devices for the perfections as may spring from too great amplitude deliveredto the speaker-by the recciving set under the influence 'of the volume control thereof.

This invention therefore has for its object to provide a drive system for the diaphragms of speakers whereby the quality and characteristics of the sound produced by the diaphragm may be changed, modified or altered. As one particular example of such change in the quality or characteristic of the sound producedby the. diaphragm, I am enabled at any given volume-setting of the receiver to control `the loud speaker, iso' that the normal reproduction may be changed at Will to accentuate the high and moderate frequencies,

and resonance and practically eliminate the'V lows, or at any given volume setting of the receiver to impro've the detail of the reproduction, enhance the sensitiveness ofthe loud 7 speaker, reproduce the overtones and natural resonance and give full value to thel lows.

Thus thesystem is particularly applicable to the reproduction of speech Where sharpness of d'einition of the spoken Words is desirable and the accentuation of moderate frequencies to the exclusion of fuzziness, overtones and resonance is materially advantageous. And the system is equally applicable to the reproductin ofsound generally such as musicaly and vocal programs Where volume is desirable and Asensitivenes's, detail, overtones,

natural resonance, and full value tothe lows are necessary to faithful reproduction.`

The invention in its broadest aspect has for its inventive" purpose to deliver, by means of suitable 'instrumentalities at one point or location in the air sound producing impulses, and to deliver ata different but adjacent point or location in the airlike sound producing impulses, the positive impulses or impulses of l compressiondelivered at the one point or location in the air being accompanied by simultaneous negative impulses or impulses of rarifacillustrating the electrical circuit for actuatpoint or location in the air, to the end that the audible sounds created by the high and moder` ate frequency impulses are sharpened and their deiinition' improved, while the audibility of the sounds created by the 'low lfrelquency impulses is impairedand fuzziness,'overtones and resonance eliminated. i y

Likewise the invention ina more limited aspect'has for its inventive purpose the accomplishment ot the above .stated result, and in addition thereto, the provision ot means for causing said instrumentalitics to deliver lat different but adjacent points or location in the air like sound producing impulses, the positive and negative impulses or impulses of compression and -rariiication produced at the one point or location in the air being a'ccompanied by simultaneous positive and negative impulses`- or impulses of compression and rarilieation delivered at the differ-ent but adjacent point in the air, to the end that the audibility of the sounds created `by the low frequency impulses is unimpaired, and the same together with the overtones and natural v resonance of the reproduced sounds are present at their normal value.

The drawing is simply illustrative of apreferred arrangement oifparts'for carrying out my vinventive purpose, vand 'si-nce other arrangements and instrumentalities may be employed for producingr alike result, I consider all such modifications, changes, alterations and variations to he Within vthe spirit of this invention when falling within the liinitand scope of the appended claims.

Referring to the accompanying drawing Figure 1 is a frontelevation ofa preferred form of the invention; f

Figure 2 is a side elevationv of the same; Figure 3 is a rear elevation of the same; Figure el; is a topy planview of the same; Figure 5 is aivertica'l longitudinl sectional View through the same'; .Y

Figure Gis a diagrammatic view of one form of diaphragm actuating system illustrating the electricaleircuits thereof Figure T -is a diagrammatic view of the system illustrating in full lines the circuit employed tor'normally actuating the diaphragm byvone motor;

Figure '8 is asimilar view of the ysystem illustrating theelectrical circuit foractuating the diaphragm by a plurality of motors Aconnected in parallel; `and Figure 9 isra similar view of the system tion only two motors have been shown though it is obvious 'that any number oi--actuating' motors may vhe employed andmay he arranged 'or connected with thed-iaphragm in .any manner best suited to the size, shape and ici.

construction of the diaphragm or to meet any 6 and 7.

R indicates a radio receiving set of any type to which the lowermost motor 5 is electrically connected by the wires 8 and 9, and is the source of the sound producing pulsating current. This isindicated as the circuit A.

Y 10 indicates a double throw double pole Aknife switch and. 11 and 12 indicate the poles oftheswitch knife 13. rThe motor 5 is also connected to the switch-knife poles 11 and 12 hy the wires 8 and `9. c

The uppermost motorA is connected to the two poles 14. and 15 of the switch 10 by wires 14 and 15 so thatwhen the switch is thrown to connect said poles 11 and 12 ot the knife 13, the two motors i and 1are connected in paral lel.A This is indicated as the circuit B.

' Connecting the motor t with the other two poles 16 and 17 of the switch'are two wires 18 and A19, and said wires are crossed so that they v.respectively pass to said switch poles 1G and- 17 on the sides opposite and reverse to those .to which the wires 14: and 15 are connected.

l/Vhen the switch knife 13 is thrown to .conncct said poles 1G and 17 with the poles 11 and 1 2 ofethe switch knife 13, thc two motors l and 'are connected in i'cierseparallel, which changes the direction of flow of the pulsating Vsaid motor' and normal laction of the diaphragm and consequently normal reproduction results. This is of course obtained when the switch knife 13'is in raised or neutr'al position. y 4

T"Vhen the switch knite-13 is thrown to connect with vthe switch poles 1li and 15, thediaphragm is ythen actuatcd at two -dii'l`erent points by the motors in the circuit B, which motors beingconnected in parallel in said /circuitimpress their impulses at two points to the diaphragm in unison sothat both motors deliver positive impulses simultaneously and negative 'impulses simultaneoi'isly.

The result is thatthe energy which the two motors et and jointly receive from the rcceiijing set is the same .as the single motor 5 rc'.- ceives when operating alone in circuit A, and

nothingin energy is gained. The acoustical] result however is that in the, case ot the two lil loo

lili) motors operating in circuit B, the impulses 'phra m under-circuit `C is particularly apfrom the two motors being delivered at two plica le to the reproduction of speech. y Y points along the diaphragm causes a more .In order that those skilled in the art may complete vibration throughout the entire diabe able to make 'and use the invention withphragin structure resulting in an increased out experimentation, it may be stated that volume, greater sensitiveness and detail and the diaphragmin the example shown in the 'a consequent improvement in the value ofthe drawing and herein described` is of the shape lows. Y and formation illustrated, and when flexed in lVith the motors 4 and 5 connected in parthat formation is 221/2 inchesv high, 111/2 allel in the circuit B, the energy delivered inches from front to back and 18 inches wuide. to each motor in the circuit is exactly one These dimensions however arev not critical half of'that delivered to the single motor 5- and are only stated by wayof description in circuit A, for any given setting of voland notby way of limitation, as I do not con,

ume control of the receiver. Likewise the sider myself llimited to, any size, shape or amplitude of the impulses of the two formation of diaphragm, nor to any particumotors isexactly one half of the ampli- .lar number or location of actuating motors tude of the impulses of the. sin le motor nor to any articular circuits, but consider A when operating alone. In consequence, the myself clear y entitled to all changes, alteratwo mojtors in circuit B are capable of recei'vtions, modifications and all instrumentalities ing and `utilizingl twice the energy of the whatsoever as may fall within the limit and single motor in circuit A, so that the sum Scope of the appended claims. e hf the amplitudes of the impulses of the two I claimmotors incircuit B will in that case be twice 1. A' device for reproducing sound includ'- that of the single mot'r in circuit A. Confing a diaphragm, a pli'iality of diaphragm sequently the two motors 4 and A5 in circuit actuating units for impressing sound produc- B may increase by a multiple of 2 the volume -ing impulses on. the diaphragm at different of sound reproduced by the diaphragm over points thereon, *afi electrical circuit for two the maiimum limit of the single motor 5 in 'of the actuatinghuniats to cause the two units circuit y .What isA said in the foregoing paragraph pulses on the aphragm simultaneously at f has equal application to the motors when contwo different points on the diaphragm, an nected in circuit C, when the switch knife `electrical, circuit for theA two actuating units 13 i'sthrown to connect with the switch poles to reverse the direction of flow ofthe pul- 16 and 17. But in this case an entirely dif- .sating current to one of the units with respect ferent diaphragm action and acoustical phe, to the other of the units, to 4cause one of the nomena result. The direction of the flow of units tol impress positive sound producing current to one of the motors being thus reimpulses at `one point4 on the diaphragm and versed in this circuit, the .impulses delivered to cause the other unitto simultaneously im- `to and impressed upon the diaphragm by the press negative sound producing impulses at motors are exactly opposed. Apositive iinanother point on the diaphragm, and an elecpulse from the motor 4e is impressed at one ftrical switch for connecting the two units in point of the diaphragm simultaneous with a. either of the two circuits.`

negative impulse-impressed bythemotor 5 2 A device for reproducing sound, includat a diierentpoint o the diaphragm, and a ing driven means for delivering sound prowave of compression-is imparted to the air ducing impulses to the air, a plurality of bythe upper portion of the diaphragm si- :driving devices for impressing simultaneous rarefaction from the lower diaphragm in the same. direction as the wave dii'erent but ladjacent points in the air, of compression; 'whereby the positive sound producingim- The result of this action in a Yproperly pulses delivered at one point in the air are designed and proportioned diaphragm is to' accompanied by simultaneous negative sound accentuatethe high and moderate fre uenproducing impulses deliveredat a different cies, sharpen the definition thereof, re ieve ut adjacent point in the air, to thev end that the reproducedsound from all .in zziness, the audibility 'of low frequency sound proovertones and resonance and ,practically ducing impulses is impaired, the definition eliminate the lows. In fact low frequencies lof moderate and' high frequency sound pro vof slight amplitude which are plainly andl ducing impulses sharpened, and resonance audibly reproduced by the diaphragm when and overtones eliminated.

actuated under the circuits A and B are env3. A device for reproducing sound, includ-- `multaneously 'accompanied-1 by a wave of positive and negative sound producing pulsaportion of the tions to the driven sound producing means at iat tfirely inaudible under circuit C. In conseing driven means for Jdelivering sound prov 'quence the high and moderate frequencies reducing impulses to the air, a plurality of produced by the diaphragm under circuit C driving devices for impressing simultaneous are clarified, refined and sharpened in definipositive and negative sound producing pultion to the end that'the actuation of the diasations to the driven sound producing means yio ducing impulses is impaired, the definition'of moderate and high frequency sound producing impulses sharpened, and resonance and c vovertones eliminated, and means for control,-

ling the driving pulsation-impres'sing devices to impress positive sound producing pulsations simultaneouslyand negative sound provducing pulsationsl simultaneously on the sound producing, means at different but adn jacent points in the air, whereby the'positive and negative sound producing impulses de-' "livered at one point in the air are simulta-` neouslyaccompaiiied by lilgeV .positive and.

negative sound producing impulses delivered at a different but adjacent point in the air, to the end that the Yaudibility of'low frequency sound producing impulses are unimvpairedand resonance and overtones repro-l duced at their truevalues.-

4. A device for reproducing sound for use in connectioii'with a source of sound produci ing pulsating current,l including a diaphragm, a plurality of diaphragm.actuating units for impressing sound producing pulsation to the diaphragm at different points thereon, two electrical circuits tor the diaphragm actuating units, in one of which circuits the pulsating current flows in the same directionto the diaphragm actuating units, in the other of the circuits the direction of i'low of the pulsating 'current to one of the diaphragm actuating unit-s whereby in the latter circuit the diaphragm actuating units impress positive sound pro-V ducing -pulsations simultaneously with negative sound producing pulsations on the diaphragm at dii'lerent points thereon, and means fo'r connecting the units in either of the two circuits.

5. A device for reproducing sound for use in connection with a source of sound producv ing pulsating current, including a diaphragm,

` a plurality ot diaphragm actuating units for impressing sound producing pulsations at dit-V erent points thereon, an electrical circuit for the j'diaphragm actuatingiunits in which cir cuit the direction of flow .oit1 the pulsating currento one of the diaphragm actuating units is reversed, whereby the diaphragmv actuating units impress positive sound pro-` ducing pulsations onthe diaphragm at one point 'and lsimultaneously impress negative f sound producing pulsations on the diaphragm at a different point thereon. A

6. A device for reproducing sound for use' in connection with a source of pulsating sound producing current, including a diaphragm, a plurality of diaphragm actuating units,

is reversed,

means for -electrically connecting the diaphragm actuatingI units together to cause the same to impress sound producing impulses in unison on the diaphragm at diii'erent points thereon,and for electrically connecting the diaphragm actuating units together to cause thesaine to impress opposed sound producing impulses on the diaphragm at .said

different vpoints thereon.

v7. A device for reproducing sound including a diaphragm, a plurality ol diaphragm actuating units connected to the diaphragm trically connecting the `units together for pulsa'ting said diiil'crent points of the diaphragm togetherand unison, and for electrically connecting the units together lfor pulsating the said'diiferent points of the diaphragm together but in'iopposition.

8` A device for reproducing sound including'a diaphragm, a plurality of diaphragm actuating` units connccted'to the diaphragm atLdiferentpoints thereon, and means for electrically connecting the-units together for .pulsatingthe said different pointsk of the dia- :and in unison and for pulsating said different points. of the diaphragm together, but in direct opposition, and means ior controlling.

the diaphragm pulsating means to pulsate the diaphragm in unison or in direct opposition.

1l. A device for reproducing sound for use in connection with a source of sound producing pulsating current, includingI a ribratory diaphragm, a yplurality of diaphragm actuat` ing units'connectcd to said diaphragm at different points thereon, a pluralitycol: electrical circuits for. said actuating units, in one of which circuits the pulsating current' flows to the actiiatingiinits in the saine direction, in another of said circuits the direction of flow of the pulsating current to one ot the units is reversed With respect to another ot the units, whereby in one of the said circuits the whole diaphragm is pulsated by the units to deliver alternate positive and negative impulses,

While in another of the said circuits the diaphragm is pulsat'ed by the units to deliver at different points thereon, means :tor elecl2. .A y device for reproducing sound in-I yeo the .diaphragm for delivering positive and negative impulses simultaneously, and means for selectively controlling the said diaphragm. actuating mean's to cause the diaphragm to deliver either positive ad'negative impulses alternately, or positive and neg(p tive impulses simultaneously;

tetimony whereof I vaiiix my signature.

CHARLES HUGH DUFFY. 

